On Fri, May 19, 2017 at 04:14:03PM +0000, co...@sdf.org wrote: > On Fri, May 19, 2017 at 03:30:19PM +0000, Chuck Silvers wrote: > > Module Name: src > > Committed By: chs > > Date: Fri May 19 15:30:19 UTC 2017 > > > > Modified Files: > > src/sys/uvm: uvm_map.c uvm_mmap.c > > > > Log Message: > > make MAP_FIXED mapping operations atomic. fixes PR 52239. > > previously, unmapping any entries being replaced was done separately > > from entering the new mapping, which allowed another thread doing > > a non-MAP_FIXED mapping to allocate the range out from under the > > MAP_FIXED thread. > > Does that have security ramifications?
It's a form of memory corruption under races. We should issue a SN for it, but I don't think MAP_FIXED is that popular in general. The case in jemalloc is now better served by using mprotect and PROT_MPROTECT, btw. Joerg